Drying apparatus



Nov. 11, 1941. w, s, SHAW "2,262,057

DRYING APPARATUS Filed March 7, 1 958 2 Sheets-Sheet l HumidisTat 1 Theme sYaT idisTaT Nov. 11, 1941.

w. s. SHAW 2,262,057

DRYING APPARATUS Filed March 7, 1938 2 Sheets-Sheet 2 Ammgg Patented Nov. 11, 1941 UNITED STATES PATENT QFFECE 8 Claims.

This invention relates to a drying apparatus generally and more specifically to an apparatus designed for use in drying leather.

The principal object of my invention is to provide an arrangement of a series of chambers whereby air may be introduced at the bottom of each chamber and removed from the top thereof, thus absorbing moisture from the leather on its upward path.

Another object of my invention is to untilize the wall partition space of the chambers as a means for conducting the air into the lower portion of said chamber;

A still further object of my invention is to provide means in at least one of the chambers whereby the rate at which the air is allowed to fiow into the first chamber may be automatically regulated.

A still further object is to provide in at least one of said chambers means for automatically regulating the temperature at which the air is introduced into the first chamber.

Other objects will appear as the description proceeds.

To the accomplishment of the foregoing and related ends said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawings and following description set forth in detail certain means for carrying out the invention, such means constituting, however, but one of various ways in which the principle of my invention may be employed.

In said annexed drawings:

Fig. 1 is a top plan view of the arrangement of chambers, a portion of each of said chambers being shown in section.

Fig. 2 is a side view of the chambers showing one of such chambers in section and the other partly in section and partly in elevation.

It is a well known fact that all tanning operations require the use of water, and it is a similarly well known fact that no hide will be considered as finished leather until a good share of the water has been removed therefrom.

The air which is utilized in removing the moisture from the hides will remove it at a rate which is dependent both upon its temperature and its humidity and it is true that the temperature of the air, within certain limits, is of less importance in drying than the degree of humidity. This is the principal reason for regulating the humidity as well as the temperature of air which is used in drying the leather.

and the final stage.

the temperature and the moisture-carrying capacity of the air. The amount of moisture taken up by one cubic foot of air is higher with increased temperature. As an example of this,

. if the-air were at a temperature of 104 F. it

would absorb twice as much moisture as at 80, or would require only about half as much air to take up the same moisture.

It is equally true, that regardless of the temperature or humidity of the air, the speed or rate of flow of such air over the leather will have a definite bearing on the amount of moisture the air is able to absorb. That is, if the air is forced into a chamber and over the leather at a fast rate of speed it will absorb less moisture than if it were allowed to move over the leather at a slower rate.

I have arranged the chambers of my drying apparatus in such a manner so that the leather in its last stage of drying will be located in the chamber wherein the air will first be introduced, and the hides in their first stage of drying will be placed in the chamber which is last visited by the air.

All leather must go through three stages of drying before it is completely finished; the first or wet tage of drying, the intermediate stage, The first or wet stage of drying is the time during which the leather is most apt to be spoiled due to the humidity of the air being too low or its temperature too high, and therein lies the necessity for rigidly controlling those conditions at that stage. As the leather approaches its final tage of drying the necessity for so controlling the air is lessened.

By placing the chambers, in which the leather passes through its first and second stages of drying, adjacent each other and extending air ducts from the last stage drying chamber to both of said other chambers, and alternately allowing the air to flow into one and then the other of said chambers I am able to pass the leather through the first and second stages of drying while it remains in one chamber, and since it is necessary to subject the leather to an intermediate process between its recond and last stages of drying, it is necessary that it will be removed from the chambers and it offers no additional hardship in replacing the leather in a different chamber for its last stage of drying.

A rather important feature to consider in the process of drying leather is the final colorof such leather. In my process I have been able to arrange means whereby a bleaching agent may T e e is, h weve a definite relation between be heated and the fumes co-m-ingled with the air which is circulated throughout the various chambers wherein the hides are hung to be dried. The bleaching agent, being mixed with the air, and coming in contact with the leather will have a tendency to bleach same. The final color desired will determine the amount of bleaching agent so mixed with the air. It will be obvious that there are several bleaching agents which may be used in this manner, depending upon the type of skins which are to be dried and bleached. For my own use I have found sulphur fumes to be one of the best bleaching agents for a particular type of hide, although it will be understood that the scope of my invention is intended to include other bleaching agents, which may be subjected to heat and have the fumes thereof given off and mixed with the air circulated through the chambers. When sulphur is used, since it kills certain forms of germ life, it will also prevent certain bacterial action from taking place.

The manner in which I intend to induce the fumes of a bleaching agent into the chambers is by placing a receptacle containing such bleaching agent near the opening of the first chamber where the air is introduced, and which is the chamber in which the last stage of drying takes place. The bleaching agent is subjected to heat and the fumes given off by such bleaching agent will co-mingle with the air in the conduit and be forced into the chamber by means of a fan or other apparatus which may be used for the same purpose.

It is to be understood that although the drawings and description illustrate a series of chambers wherein only one chamber is used for each of the stages of drying, it is within the scope of my invention that two or more chambers may be used where one is now used if it becomes necessary to utilize more space for the hanging of the hides.

It is also very necessary in the drying of leather that the air be distributed equally throughout the chamber and in order to accomplish this I have placed screens both below and. above the hides so that the air coming into the chamber in the bottom will pass under one screen and must pass through the second screen before it is allowed to pass out of the chamber.

Referring now more specifically to the drawings and more especially to Fig. 1, the chamber generally designated by the numeral I is the one into which the air first flows, but in which the leather is placed for its last stage of drymg. The manner in which the various air ducts are placed and the openings which are shown in Fig. 1 disclose the air flowing from chamber I into the chamber generally designated by the numeral 2. In this chamber the leather is undergoing its intermediate drying stage.

The chamber designated by the numeral 3 indicates the one in which the hides are placed in a wet condition, containing approximately 50% water, and is the chamber in which the leather undergoes its first stage of drying. It isin this stage that the operator must be most careful to have the temperature and the humidity of the air suitable for the condition of the leather in order to avoid drying the leather too fast which tends to oxidize and darken the color, and make the product brittle. Since this is the chamber which must control the temperature and humidity of the air it is obvious that the humidos'tat and thermostat must be placed in the chamber wherein the leather undergoes the first stage of drying.

In accordance with my invention the air enters into the room I through the chamber wall 4 and is forced into said chamber in the usual manner by means of a fan 5 and is heated before so entering by steam pipes 6.

As will be more clearly seen in Fig. 2, the air will enter at the bottom chamber I, as designated by the arrow in Fig. 2.

The air then is allowed to pass upwardly through the screen I in order to give it an equal distribution throughout the chamber.

Near the top of the chambers and above the hides is placed a second screen 8 which preferably has its passageways therethrough slightly smaller than in the lower screen in order that the air will have no tendency to rush upwardly. The purpose of said upper screen will be more to hold the air back, thus aiding in providing a more even distribution thereof.

The air then moves upwardly through a duct 9 in the top of the chamber and passes through a passageway I 0 of said duct wherein a small booster fan H is placed. From this point the air then passes through a second passageway I2 into the wall space of chamber 2 and thence downwardly as indicated by the arrows in Fig. 2 where it is allowed to pass into the chamber at the bottom thereof and beneath a similar screen I3.

After the air has absorbed a predetermined amount of moisture from the hides located in chamber 2 it passes upwardly through the screen I4 and into the duct I5 where it is allowed to enter a small passageway I6 which contains another booster fan I1, and then passes into the wall of chamber 3 and downwardly therethrough where it is allowed to escape near the floor thereof and beneath similar screens as in chambers I and 2. As in the other chambers, after the air has pass-ed upwardly through the screen in chamber 3 and has absorbed a definite amount of moisture from the hides in said chamber it then passes upwardly into the air duct I8 and thence outwardly by the aid of the booster fan I9. From this point the air may be treated and carried back to its original starting point and reused.

The above passage of air has been explained when chamber 3 is used for the first stage of drying, chamber 2 for the second stage and chamber I for the last stage; although chamber I is always used for the last stage of drying, chambers 2 and 3 may be alternately used for first and second stages. Assuming now that the leather in chamber 3 has been dried the first time, and the leather in chamber 2 has been passed through its second stage of drying, the hides from chamber 2 will then be removed and be processed with intermediate treatment after which they will be placed in chamber I for the final stage of drying and wet hides will be placed in chamber 2 for the first stage of drying.

When this is done the air leaving chamber I obviously must pass first into the chamber 3 since the leather in this chamber is now ready for its second stage of drying. To direct the air in this manner the gates 20 and 2| of chamber 2 will be moved over their respective openings thus preventing any air from entering the chamber at that point. Likewise the gates 22 and 23 will be moved so that the openings which they cover will permit air to flow from the wall chamber into the room. Furthermore, the gates 24 and 25 will be moved to cover their respective openings and the gates26 and 21. will be opened so that the proper direction of air may be had.

Similarly now, the gates 28 and 29 in chamber 3 will be opened, and the gates 30 and 3| will be closed. The gates 32' and 33 of the air duct 15 will be opened and the gates 34 and 35 of the air duct l8 will be closed. After this has been accomplished the air flow from chamber I will then be through the wall of chamber 3, upwardly As has been stated above,. an important factor I in drying of leather is the humidity of the air which is allowed to pass over said leather and allowed to absorb moisture therefrom. and it was also stated that the speed of the air will determine the amount of moisture it is able to absorb. For this purpose a humidostat 36 is placed in chamber 3 and is electrically connectedby means of a rheostat 31 and battery 38 to the fan 5. Said humidostat then, will automatically control the speed of the fan 5 which in turn will regulate the rate of flow of air into chamber I. That is, if it is desirable to have the air absorb more moisture the speed of the fan 5 will be made slower in order that the air will move more slowly and thus absorb more moisture.

In view of the fact that chambers 2 and 3 may be used alternately for the first and second stages of drying a second humidostat 39 is placed in chamber 2 and the respective humidostats 36 and 39 may be alternately connected to operate the fan 5 by means of the switch 40.

It should be noted at this point that in order to assure an even distribution of air through every chamber, and a distribution which will correspond to the variation in speed of the fan 5 due to the operation of a humidostat, the booster fans should be connected with the fan 5 so that when the speed of the first fan varies, the speed of all of the booster fans will also vary accordingly. This particular arrangement is not shown in the drawings but it will be understood that the fans would be multiple speed fans and would be operated from a common rheostat or other speed regulating device.

Another manner in which the air may be regulated according to the variation in speed of the fan 5 would be to use constant speed motors on the booster fans and provide means for automatically regulating the gates so that they will open up more or less as the humidostat calls for more or less air in order to increase or decrease the humidity in the first stage of drying. This method, however, I do not consider as satisfactory nor as economical as the method of varying the speed of the motors and fans.

Since the temperature of the air entering into the chamber wherein the leather is undergoing its first stage of drying is an important factor, a thermostat 4| is placed in said chamber and is electrically connected through a battery 42 and a valve 43 to the steam pipes 6, thus controlling the temperature of the air entering chamber I.

In the same manner as above described with regard to the humidostat, chamber 2 also contains a thermostat 44 and either of these. thermostats may be connected through the electric valve 43 by means of the switch 45.

As hereinbefore explained, I have been ableto supplement my invention with additional means for admixing a bleaching agent with the air which is'induced into: the various chambers, if it is desired to bleach the leather to a particular color. The manner in which this step in. the process is carried out is to provide a receptacle 46 in the conduit and preferably in front of the fan 5. The sulphur or other bleaching agent, will be placed in the receptacle and heated so as to give off fumes or gas. The gas so given off, due to the heating of the bleaching agent, will be co-mingled with the. air which has previously been heated and will then be forced into the various chambers of the serieswhere it will contact thehides and accomplish the desired result.

From the above description it will be seen that I have constructed a novel apparatus for drying leather in the minimum amount of time and a construction wherein the. temperature and humidity of the air entering the chamber wherein the leather is undergoing its last stage of drying will be directly controlled by conditions at their critical period in the chamber wherein the leather is undergoing its first stage of drying. Also an arrangement has been devised whereby it becomes unnecessary to touch the leather between its first and second stages of drying.

Other modes of applying the principle of my invention may be used instead of the one here explained, change being made as regards the apparatus herein disclosed, provided, however, that the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. An apparatus of the class described comprising a plurality of chambers, means for inducing an air current into the bottom of said chambers and out of the top thereof, means for heating said air, means for conducting said air between the chambers, means in one of said chambers other than the one where the air is first introduced to automatically regulate the temperature of said air at its point of introduction into the first chamber.

2. The combination of elements as defined in claim 1 combined with means, in the same chamber with said temperature regulator, to regulate the rate at which said air is introduced into said firstchamber.

3. An apparatus for drying leather which comprises three chambers for the three stages of drying, the walls of said chambers adapted to have air passed therethrough, means for heating said air, overhead ducts to conduct air from the first chamber to the second and from the first chamber to the third, other ducts to conduct air from the second chamber to the third and from the third chamber awaytherefrom, means in said second and third chambers to alter the course of said air whereby it may be caused to flow from the first chamber to the second and then to the third or from the first chamber to the third and then the second, means in the chamber from which the air is finally removed to regulate the temperature of the air entering the first chamber, and means inthe same chamber to regulate the rate of fiow of air into said first chamber, said last two named means being sensitive to the temperature and humidity respectively of the chamber from which the air is finally removed.

4. The combination of elements as defined in claim 3 said means to alter the course of said air including gates cooperatively associated with the wall openings in said second and third chambers whereby the openings in said chambers may be alternately closed to prevent air from entering therein.

5. A leather drying apparatus comprising a plurality of chambers connected in series, means for inducing a current of air successively through said chambers, means for heating said air, said air necessitating a predetermined moisture content when it reaches the last chamber, and means sensitive to the temperature and humidity of said last chamber to regulate the condition of the air entering the first chamber whereby the air reaching the last chamber will have the said predetermined moisture content;

6. The combination of elements defined in claim 5, combined with air ducts connecting said chambers, and means therein to modify the succession of chambers through which said current is conducted.

'7. An apparatus of the class described comprising, a plurality of chambers having interconnecting air ducts, means for inducing a current of air into the bottom of each chamber and out of the top thereof, said air passing continuously from the first to the last chamber, means for heating said air, a humidostat and a thermostat in the last chamber to regulate the rate of flow and the temperature respectively of the air current as it enters the first chamber, whereby the rate at which moisture will be removed from articles located in the various chambers may be controlled.

8. An apparatus for drying leather which comprises, a plurality of chambers in which the leather is located for the various stages of drying, air ducts connecting the various chambers, means for conducting a current of air continuously through said chambers and said ducts, means for heating said air, and means located in the last chamber to which the air passes which is sensitive to both the temperature and humidity of said last chamber, to control the temperature and rate of flow of said air as it enters the first chamber, whereby the leather will be dried at a predetermined rate in each chamber, but said rate will be different for each chamber.

WILLIAM S. SHAW. 

